基于草本群落、牧道特征对野果林放牧干扰强度的评价

Evaluation of grazing disturbance intensity in wild fruit forests based on herbaceous community and grazing path characteristics

客观、综合评价野果林放牧强度对正确认识林牧矛盾,制定科学合理的放牧制度具有重要意义。目前的研究主要集中在野果林放牧对植被群落特征和物种多样性影响上,然而野果林放牧活动本身的关注以及放牧强度的量化方法等方面尚不明确。基于此以新疆野果林6个典型放牧区为试验地,分析对比各放牧区的草本群落组成结构、生长特征、物种多样性以及牧道特征,并筛选出评价放牧干扰强度的主导因子,对其放牧干扰强度进行定量评价。结果表明:(1)草本群落特征方面,杏花沟物种数最多,且以禾本科种属植物为优势种;但莫乎儿沟草本密度比杏花沟高1.26%;各放牧区物种多样性水平存在显著差异,与其他放牧区相比,莫乎儿沟Shannon-Wiener多样性、Simpson优势度指数最高,分别为1.92、0.84,而吾都布拉克沟的Pielou均匀度指数最大;(2)牧道特征方面,伊勒格代沟的牧道密度显著大于匹里青沟,分别为19.23%、14.77%,而杏花沟的牧道宽度显著大于大西沟;在牧道分布格局上,除匹里青沟外,其他放牧区皆为均匀分布;(3)相关性分析表明草本群落结构特征、物种多样性水平及牧道特征指标间均存在较好的相关关系,对其12个指标主成分分析筛选出草本群落盖度、生物量、Shannon-Wiener多样性指数、Simpson优势度指数以及牧道密度与格局指数可作为评价放牧干扰强度的主导因子,依据牧压指数判定杏花沟与莫乎儿沟为轻、中度放牧干扰,大西沟、伊勒戈代沟、吾都布拉克沟与匹里青沟为重度或极度放牧干扰。当前新疆野果林整体受到放牧重度干扰,急需优化或者制定科学的放牧制度维护野果林的可持续发展。

The contradiction between grazing and vegetation resource protection in wild fruit forest area has always been the core issue in the development of local animal husbandry.The objective and comprehensive evaluation of grazing intensity of wild fruit forests are of great significance to correctly understand the contradiction between forest and grazing and to formulate a scientific and reasonable grazing system.The current research mainly focuses on the effects of wild fruit forests grazing on vegetation community characteristics and species diversity.However,the attention of wild fruit forest grazing activities and the quantitative methods of grazing intensity are still unclear.This study took six typical grazing districts of wild fruit forests in Xinjiang as experimental sites,analyzed and compared the composition structure,growth characteristics,species diversity and grazing⁃path characteristics of herb communities in each grazing district,screened out the dominant factors for evaluating grazing disturbance intensity,and quantitatively evaluated the grazing disturbance intensity.The results showed that the number of species in Xinghuagou was the largest and Gramineae species were the dominant species.However,the herb density of Mohuergou was 1.26%higher than that of Xinghuagou.There were significant differences in species diversity among grazing districts.Compared with other grazing districts,the Shannon⁃Wiener and Simpson index of Mohuergou were the highest,which were 1.92 and 0.84,respectively,while the Pielou index of Wudubulakegou was the highest.In terms of the characteristics of grazing⁃path,the grazing⁃path density in the Yilegedaigou was significantly higher than that in the Piliqinggou,which was 19.23%and 14.77%,respectively,while grazing⁃path width in the Xinghuagou was significantly larger than that in the Daxigou.In the distribution pattern of grazing⁃path,except for Piliqinggou,other grazing districts were evenly distributed.The correlation analysis showed that there was a good correlation between the structural characteristics of herbaceous community,the level of species diversity and the characteristics of grazing⁃path.The principal component analysis of the 12 indicators screened the herbaceous community coverage,biomass,Shannon⁃Wiener index,Simpson index,grazing⁃path density,and Morisita index could be used as the dominant factor to evaluate the intensity of grazing interference.According to the grazing pressure index,Xinghuagou and Mohuergou were judged to be light and intermediate disturbance,while Daxigou,Yilegedaigou,Wudubulakegou and Piliqinggou were severe or extreme disturbance.The results indicated that the wild fruit forest in Xinjiang was seriously disturbed by grazing,and it was urgent to optimize or formulate a scientific grazing system to maintain the sustainable development of wild fruit forest.